High-temperature hot water systems, which operate at temperatures typically exceeding 350° F. and pressures over 300 psi, are commonly used in large, hot water distribution systems. These systems may be, for example, district heating, which is a system used for distributing heat that is generated in a central location for residential, commercial, or government heating requirements. For example, university campuses, industrial manufacturing facilities, prisons, military or government bases or facilities, and may have district high-temperature hot water heating systems. As another example, they could be systems requiring high-temperature process applications including heat transmission for air and roller driers and washing equipment in kitchens, and sterilizers in hospitals or labs.
Currently, high-temperature hot water systems require the use of manholes, including large, underground concrete vaults that contain mechanical piping and valves exposed within the vault. To actuate these high-temperature valves, workers must remove the manhole covers and descend below ground into the vaults. However, workers are often reluctant to do so. These vaults are often confined spaces that are dark and hot, and require extra safety precautions and permits to enter and activate, close, adjust, and maintain the valves. These vaults can also be complex, with a plethora of different valves placed within the same area. This can make it difficult for workers to identify the high-temperature valve(s) that should be adjusted.
While buried valve assemblies have been used in some low-temperature water systems, these assemblies are not capable of handling high-temperature hot water. In particular, low-temperature buried valves cannot accommodate thermal expansion and do not allow drainage in the event ground water enters the system and comes in contact with the pipe, potentially causing flashing and system failure. They would therefore be incapable of use in a high temperature environment. Thus, what is needed is a direct buried valve, with surface access boxes to activate and control the valves, allow drainage, which can be used in high temperature water systems.